Should we retrieve the Zakat amount that was disbursed to a person who died after receiving the amount, and whose well-off family offered to return it?

If a person was poor and eligible for zakat (definition) when it was given to him, he owned it the moment he took possession of it. It absolved the one who gave it, and you have no right to reclaim it from him, nor from his heirs after his death, nor after his state of poverty ceased. It is known that the aforementioned amount belongs to the deceased's heirs, not to his wife's family. The zakat was valid on your part as long as the deceased was poor at the time it was given to him, even if he became wealthy, or even if you gave it to him assuming he was poor when he was actually rich, and this is the opinion of most scholars.